Optical microstructures are widely used in consumer and commercial products. As is well known to those having skill in the art, optical microstructures may include microlenses, optical gratings, microreflectors and/or other optically absorbing, transmissive and/or reflective structures, the individual sizes of which are on the order of microns, for example on the order of about 5 μm to about 1000 μm in size.
The fabrication of large arrays of optical microstructures is currently being investigated. As used herein, a large array of optical microstructures contains at least about one million optical microstructures and/or covers an area of at least about one foot square. For example, large arrays of microlenses may be used in computer displays (monitors) and/or projection televisions. It will be understood that an array can have uniform and/or nonuniform spacing of identical and/or nonidentical microstructures.
Unfortunately, however, severe scaling barriers may be encountered in attempting to fabricate large arrays of optical microstructures. These scaling barriers may make it difficult to efficiently produce large arrays of optical microstructures with acceptable manufacturing yields.
Several barriers may be encountered in attempting to scale optical microstructures to large arrays. First, the time to master a large array may be prohibitive. In particular, it is well known that optical microstructures may be initially imaged in a “master”, which may then be replicated in one or more second generation stampers to eventually produce large quantities of end products. Unfortunately, it may be difficult to produce a master for a large array of optical microstructures within a reasonable time. For example, calculations may show that it may take years to create a single master for large screen rear projection television. These mastering times may be prohibitive for viable products.
It also may be difficult to image certain optical microstructures that may be desired for many applications. For example, computer displays or projection televisions may employ large arrays of microlenses, wherein each microlens comprises a hemispherical section, which can include a sub-hemisphere (subtends less than 180°), hemisphere (subtends about 180°) or super-hemisphere (subtends more than 180°). However, it may be difficult to master a large array of hemispherical sections using conventional photolithographic techniques. Finally, it may be difficult to efficiently replicate masters containing large arrays of optical microstructures to produce stampers, so as to enable high volume production of optical microstructure end products for display, television and/or other applications.